Class-ify ==>>.
scalaJSONObjectPLens and scalaJSONArrayPLens is deprecated

because `scala.util.parsing.json` is deprecated from Scala2.11
https://github.com/scala/scala/commit/3e1a075a7e8b9178
tweak scaladoc. add scalaz.Optional
Merge pull request #454 from xuwei-k/deprecated-std-json

scalaJSONObjectPLens and scalaJSONArrayPLens is deprecated
update DeveloperGuide
separate GenerateTupleW
classify TupleNOps
more classify some traits
Fix stack overflow in issue #456
Merge pull request #458 from xuwei-k/classify

more classify some traits
Merge pull request #455 from xuwei-k/classify-TupleNOps

classify TupleNOps
Fix a few remnants of variance in `IndexedContsT`

Changed two `<:<`s to `=:=`s.
add new method MonadPlus#separate
MonadPlus#separate test
avoid allocate unnecessary new objects
explicit return type annotations
Merge pull request #462 from xuwei-k/explicit-return-type

explicit return type annotations
add more explicit return type. s/private[scalaz] trait/private trait/
add DisjunctionTest
fix issue where x would be evaluated twice.

same issue #352